The inventive concept relates to a semiconductor device, and more particularly, to a semiconductor device which is capable of reducing an increase in contact resistance Rc between a metal contact and a plug, and reducing the difficulty in forming the plug.
As semiconductor devices are miniaturized, the pitch of metal contacts may be decreased. However, since it can be difficult to reduce a photo misalignment margin in a photolithography process below a predetermined level, misalignment between a metal contact and a plug formed thereon can be generated. In this regard, misalignment may occur in practice.
Misalignment may cause increase in leakage current between the metal contact and the plug, deterioration of a breakdown voltage, and deterioration of time dependent dielectric breakdown (TDDB). In order to address the problem, a blocking SiN hole (BSH) scheme can be used. Since the metal contact and the plug are separated by a silicon nitride (SiN) layer, the increase of the leakage current or the deterioration of the breakdown voltage may be prevented or reduced even if the metal contact and the plug are misaligned.
Generally, however, misalignment of the metal contact and the plug can still occur despite use of the BSH scheme, and the width of the contact surface between the metal contact and the plug can be reduced and thus the contact resistance Rc between the metal contact and the plug may be increased. In addition, since a Cu filling process is performed for two layers—two metal contacts—when forming the plug, the Cu filling process is performed on a dual damascene pattern, which may increase the difficulty of the Cu filling process.